Technical Field
The present disclosure relates to an electrochromic element.
Description of the Related Art
Electrochromism is the phenomenon displayed by some materials of reversibly changing color as a redox reaction reversibly occurs in the materials in response to a voltage. Electrochromic elements are known that reversibly change color as a redox reaction occurs therein. Generally, an electrochromic element includes a pair of electrodes facing each other with an ion-conductive electrolyte layer disposed between the electrodes. In a case in which a reduction reaction occurs in proximity to one of the electrodes, an oxidization reaction (i.e., the reverse reaction of the reduction reaction) occurs in proximity to the other one of the electrodes. When applying such an electrochromic element to a transparent display device, or a color developing device using a laminated layer of cyan, magenta, and yellow color developing layers, the electrochromic element needs to contain a material that can become colorless and transparent.
Examples of such a material include viologen compounds that exhibit transparency when in a neutral state and develop color when in a reduced state. In addition, triarylamine compounds are known as oxidizable color-developing electrochromic materials that exhibit transparency when in a neutral state and develop color when in a reduced state.